Fiber optic lasers including both laser amplifiers and laser oscillators (referred to throughout this application as simply fiber lasers) require significant pumping energy supplied by directing the pumping energy into the core of the fiber optic element. Since the core of the fiber optic element is quite small, typically 5 .mu. in diameter, aligning the pumping source is difficult. Various techniques including the use of lenses and precise alignment tolerances are necessary to properly couple the pumping source into the core of the fiber optic element. Further, since the cores are so small the amount of power that can be introduced is quite limited. This problem was solved in fiber optic arrangements by using a double cladding design which increased the area available for coupling in the pumping source and allowed the energy to repeatedly internally reflect in the first cladding transversely passing through the core of the fiber optic element until the energy was absorbed to promote the action of the fiber optic lasers. See U.S. Pat. No. 4,826,288. Even in this approach, however, the coupling surface is confined to the area of the first cladding and so larger, more powerful pumping sources such as phased array diode lasers and other high-power sources cannot be easily accommodated.
More recently, end pumped channel waveguide lasers have been constructed in planar format. But these too suffer from the difficulties in aligning the pumping source to the end of the channel waveguide which is typically 5 .mu. square. While such devices are very appealing because of their superior manufacturability, the difficulty in pump coupling and the limited pump power which can be coupled has been a major drawback. This is especially problematic because pumping sources such as pumping lasers are constantly being improved to provide even greater power but with ever-increasing emitting apertures, thus making end coupling even more difficult.